Yup. What you said.

I never accept a LI connection request that isn't from someone I know and have professional respect for, or at least someone who personalized their request enough to make it clear why they think it makes sense for us to connect.

And just working in the same industry doesn't quite cut it.

Even if I do accept your request, if I can't recall why because in the many years since I accepted your request you haven't sent me a single message, I'll recommend you for a job around the 12th of never (that's a date on whatever calendar you favor).

Having said that, I stay on LI because it got me an unsolicited $165k gig once, and even if those only show up once a decade, the ROI is great :).